9.1a Oxidation state and naming

Definition of oxidation and reduction
Machine generated alternative text:

Oxidation state

an increase in oxidation number represents oxidation, and a decrease in oxidation number represents reduction

Example:

Machine generated alternative text:21-12(g) + 02(g) —‘ 2H20(1), t +‘iI

Hydrogen has been oxidised (oxidation state has increased from 0 to 1) and oxygen has been reduced (oxidation state decreased from 0 to -2)

 

Exceptions you have to memorize

O is always -2 except for in H2O2

H is always +1 except for in NaH and similar compounds where H goes at the end

Note that in an ionic compound, the + ion is always on the left, - ion is on the right

 

Naming of metal using oxidation state

  • Some elements exhibit different oxidation states so sometimes this information is used in the name of the compound
  • Roman numerals that correspond to the oxidation number are used in brackets after the name of the element, eg copper(I) oxide and copper(II) oxide

Example:

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